It is known from Canadian Pat. No. 913,328 to provide a method of producing chlorine dioxide which comprises:
A. ESTABLISHING IN A REACTION ZONE AN AQUEOUS REACTION MEDIUM CONTAINING DISSOLVED QUANTITIES OF SODIUM CHLORATE, SODIUM CHLORIDE AND HYDROCHLORIC ACID, THE AQUEOUS REACTION MEDIUM BEING SUBSTANTIALLY SATURATED WITH SODIUM CHLORIDE,
B. CONTINUOUSLY FEEDING HYDROCHLORIC ACID OR HYDROGEN CHLORIDE TO THE AQUEOUS REACTION MEDIUM,
C. CONTINUOUSLY MAINTAINING THE REACTION MEDIUM AT ITS BOILING POINT AT THE ABSOLUTE PRESSURE THEREON AT A TEMPERATURE BELOW THAT ABOVE WHICH SUBSTANTIAL DECOMPOSITION OF CHLORINE DIOXIDE OCCURS,
D. CONTINUOUSLY MAINTAINING THE REACTION ZONE UNDER A SUBATMOSPHERIC PRESSURE SUFFICIENT TO MAINTAIN THE REACTION MEDIUM AT ITS BOILING POINT,
E. CONTINUOUSLY GENERATING CHLORINE DIOXIDE, CHLORINE AND SODIUM CHLORIDE IN THE REACTION MEDIUM,
F. continuously removing from the reaction zone a gaseous mixture of chlorine dioxide, chlorine and steam wherein the volume ratio of steam to chlorine dioxide is greater that that below which substantial decomposition of chlorine dioxide occurs, PA1 G. continuously depositing the generated sodium chloride from the reaction medium in the reaction zone, PA1 H. removing the deposited sodium chloride from the reaction zone, and PA1 I. continuously maintaining the volume of liquid in the reaction zone substantially constant.
The acidity of the reaction medium as provided by the hydrochloric acid is generally about 0.1 normal and this results in a satisfactory rate of chlorine dioxide production.